The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
In order to operate and control a vehicle, the vehicle is equipped with various electric and mechanical devices such as an engine, a transmission, a fuel tank, wheels etc., and electrical cables and connectors are used to transfer electric power or signals between those devices. Depending on locations of those devices and electric components (connectors, cables), those are exposed to different environments and thus are specifically designed to be suitable for the use in specific locations and conditions.
For example, a fuel tank to store fuel for a vehicle includes a fuel pump to discharge the fuel from the fuel tank to an engine of the vehicle through a fuel line, and the delivered fuel is injected into cylinders of the engine to be burned to generate power to run the engine. The fuel pump operates with electric power transferred from a battery or a generator via electric power cables, and the power cables are connected to the fuel pump and other sensors like a fuel level sensor that gages the level of fuel inside the fuel tank. As the fuel tank is filled with fuel, those electric cables and connectors disposed inside of the fuel tank are in direct contact with the fuel.
Since the electric cables are electrically connected to the fuel pump and sensors via electric connectors, the connections between the electric cables, the connectors, and electrical terminals for the fuel pump and sensors need a certain type of sealing that inhibits or prevents the entry of fuel into the connectors for the electric terminals and cables of the pump and sensors.
Permeation of fuel into the connectors causes the electrical terminals of the pump or the sensors to contact with the fuel and results in chemical and/or electrolytic corrosion of the electric terminals of the pump and sensors. In particular, highly conductive fuel such as alcohol-mixed fuel or ethanol-fixed fuel dramatically increases conductivity than ordinary gasoline, and thus the electrolytic corrosion of the electric terminals becomes much more problematic.
In general, electrolytic corrosion occurs when two terminals with opposite polarities are exposed to fuel in the same space. For example, if a positive terminal and a negative terminal coexist in the same space (e.g., a chamber) of an electric connector, a current path is formed via the fuel when it has entered into the chamber. As a result, electrochemical corrosion (electrolytic corrosion) is caused in both the terminals and eventually breaks in electric continuity between the terminals housed in the electrical connector. The alcohol blended fuel or the ethanol type fuel escalates electrolytic corrosion. We have discovered that such electrolytic corrosion is more easily produced if a distance between both the terminals (i.e., positive and negative terminals) which coexist in the same chamber of the electric connector is shorter and thus separation of the terminals and longer distance between the terminals are desired.